Microbiology

Question 1

Eukaryotes Vs. Prokaryotes

Answer 1

Question 2

Bacteria that lacks cell wall

Answer 2

mycoplasma

Question 3

Gram +

Answer 3

thick peptidoglycan layer
- teichoic acid
- aid in bacterial adhesion
- act as an antigen
- stain PURPLE

Question 4

Gram (-)

Answer 4

• stains RED
• thin peptidoglycan
• Lipopolysaccharide (outer protective layer)

Question 5

What does the lipopolysaccharide consist of?

Answer 5

“LPS - O”

• Core polysaccharide (repeating sugar)
• lipid A (acts as an endotoxin)
• O side chain (repeating sugar)

Question 6

Which antibiotics target peptidoglycan layer?

Answer 6

Bactrim
Vancomycin
Penicillin
Cephalosporins

Question 7

Phases of bacterial growth

Answer 7

• Lag phase = cells active and grow without dividing
• Log phase = cells growing and dividing. Antibiotics most effective during this stage
• Stationary phase = Cell number remains constant. begins when essential nutrients for bacterial survival becomes depleted
• Death phase = population declines as the dead cells outnumber the living cells

Question 8

Life cycle of bacteria

Answer 8

“ICD”

I = initiation period = bacterial elongation
C = bacterial chromosome replicate
D = Division period, cell wall thickens and divides into 2 daughter cell via pinching

Question 9

Aerobic organisms

Answer 9

requires O2 for growth

Question 10

Obligate aerobes

Answer 10

COMPLETELY dependent on O2 for survival
- O2 is the final electron acceptor

Question 11

final electron acceptor for the electron transport chain

Answer 11

O2

Question 12

Anaerobic organism

Answer 12

CANNOT survive in the presence of O2

Question 13

Facultative anaerobes

Answer 13

can survive in presence of O2 or without it (prefers O2 environment)

Question 14

Spore formation

Answer 14

• gram + rods can form endospores when nutrients are limited
• Endospores have no metabolic activity
• provide protection against excessive heat, UV, chemicals and dehydration

Question 15

ex. of spore-forming bacterial

Answer 15

Bacillus anthracis, clostridium botulinum

Question 16

Genetic mechanism of bacteria

Answer 16

Transformation = take up free DNA into genome

Transduction = transfer of bacterial DNA from one cell to another via bacteriophages (virus that infects bacteria)

Conjugation = genetic transfer via direct cell-to-cell contact. involves transfer of plasmids via conjugation bridge

Question 17

Transposition

Answer 17

Transposition is a genetic process that involves the movement of specific segments of DNA within a genome. It’s like a cut-and-paste operation for genetic material inside a cell.
- aka jumping genes

• simple = move around within genome
• complex = consist of other genes (ex drug resistance)
• Pathogenicity islands = large transposons that contain all genes necessary for certain pathogenic bacteria (can cause dz)

Question 18

Gram + bacteria

Answer 18

Question 19

Gram - bacteria

Answer 19

Question 20

Spirochetes

Answer 20

Question 21

Why is mycobacterium resistant to penicillin?

Answer 21

Because they cannot produce peptidoglycan to make the cell wall

Question 22

What temperature is the autoclave set at?

Answer 22

121 C or 250 F for 15 mins